Radiation refrigeration nanofiber membrane composite garment material and preparation method thereof

Abstract

The invention discloses a radiation refrigeration nanofiber membrane composite garment fabric and a preparation method thereof.Polyvinylidene fluoride-co-hexafluoropropylene is adopted as a matrix, nano silicon dioxide particles are added, and a P (VDF-HFP / SiO2 composite nanofiber membrane is prepared. Vinyl acetate copolymer EVA hot melt adhesive non-woven fabric is adopted as a middle layer, and a nanofiber membrane and a common fabric are compounded through a hot pressing process, so that the prepared composite material not only shows excellent radiation refrigeration capacity, but also enhances moisture absorption and sweat releasing functions by means of unique structural attributes of the nanofiber membrane, and has good radiation refrigeration performance. According to the radiation refrigeration nanofiber membrane and garment fabric composite material, excellent air permeability is maintained, and meanwhile, a more effective cooling effect is achieved, so that the radiation refrigeration nanofiber membrane and garment fabric composite material is particularly suitable for producing high-performance garments, and is particularly suitable for outdoor thermal management and sun protection garments.

Description

Technical Field

[0001] The invention belongs to the technical field of textiles for clothing, and in particular relates to a radiation cooling nanofiber membrane composite clothing fabric and a preparation method thereof. Background Art

[0002] As the economy continues to develop, global energy consumption has shown an increasing trend year by year, leading to excessive carbon emissions and increased air pollution. These environmental problems have a direct impact on climate change and may cause frequent extreme heat wave events in the coming decades, greatly increasing the global demand for cooling energy. In response to this challenge, passive radiative cooling technology, as an effective and renewable solution, provides a new perspective to alleviate the world's growing cooling demand. Radiative cooling technology has been widely used in energy-saving buildings, photovoltaic cooling, energy collection, and personal thermal management. It can achieve cooling effects without any external energy input, providing a feasible path to solving global cooling challenges.

[0003] Seeking more efficient and energy-saving solutions has become a research hotspot. By innovatively adjusting the surface and internal structure of textile fibers, not only can the wearability of textiles be maintained, such as their moisture permeability and breathability, but the multi-scale disordered porous structure of fibers can also be used to improve the transparency of infrared radiation in the human body and the backscattering ability of visible light. This structural design maximizes the reflection of solar radiation and enhances the loss of thermal radiation from the human body, while improving the water absorption and breathability of textiles, thereby effectively achieving personal cooling.

[0004] Although P(VDF-HFP)-based radiative cooling materials show potential application value, they still face problems such as large fiber thickness, poor moisture permeability, unstable fiber structure and low UV reflectivity. In addition, most of the current processes for preparing porous P(VDF-HFP) nanofiber membranes focus on functions such as adsorption and filtration, and often ignore the effect of color changes on material properties. For example, the porous P(VDF-HFP) nanofiber membranes reported in previous studies often appear light yellow. This color change may have an adverse effect on the reflectivity of the material in the ultraviolet visible light wavelength range, thereby reducing the overall cooling effect. Summary of the invention

[0005] Technical issues solved:

[0006] The present application aims at the deficiencies in the prior art and solves the current technical problems such as fiber thickness, moisture permeability, fiber structure stability and ultraviolet reflectivity. In view of the technical challenges of the cooling function and comfort of fabrics on the market, a radiation cooling nanofiber membrane composite clothing fabric and a preparation method thereof are provided. By controlling the change in fiber color, the reflectivity in the ultraviolet and visible light wavelength range is maximized. Silica is added to the nanofiber membrane, which not only helps to further enhance the ultraviolet reflection ability of the fiber membrane and enhance the cooling effect, but also silica can enhance mid-infrared emission and improve the radiation cooling efficiency. It not only effectively responds to the growing cooling demand, but also provides a new efficient and environmentally friendly approach for the field of personal thermal management.

[0007] Technical solution:

[0008] To achieve the above objectives, this application is implemented through the following technical solutions:

[0009] A method for preparing a radiation cooling nanofiber membrane composite clothing fabric, the steps are as follows:

[0010] The first step: using polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) as a matrix and doping nano-SiO2 particles uniformly distributed in the P(VDF-HFP) copolymer to obtain a spinning solution, and preparing a P(VDF-HFP) / SiO2 composite nanofiber membrane, i.e., a radiation cooling nanofiber membrane, from the spinning solution by electrospinning technology;

[0011] Step 2: The P(VDF-HFP) / SiO2 composite nanofiber membrane and clothing fabric are compounded with EVA hot melt adhesive non-woven fabric to form a stable composite material, namely, the radiation cooling nanofiber membrane composite clothing fabric.

[0012] Furthermore, in the first step, the spinning solution is prepared by dissolving P(VDF-HFP) in a mixed solution of DMF and acetone at 50°C to 60°C.

[0013] The mixture is stirred and mixed for 1 h to 2 h, and then nano-SiO2 particles are added, and degassing is performed under 60 to 100 W ultrasound for 30 to 60 min; the nano-SiO2 particles are hydrophobic silicon dioxide.

[0014] Furthermore, the mass ratio of nano-SiO2 particles: P(VDF-HFP)=4-5:100.

[0015] Furthermore, the molar ratio of DMF to acetone in the mixed solution of DMF and acetone is DMF:acetone=6:4.

[0016] Furthermore, the specific preparation method of the P(VDF-HFP) / SiO2 composite nanofiber membrane is as follows:

[0017] S1, adding polyvinylidene fluoride-co-hexafluoropropylene P (VDF-HFP) pellets into a mixed solution of DMF and acetone, and magnetically stirring at 50° C. to 60° C. for 1 h to 2 h to obtain a softened P (VDF-HFP) matrix;

[0018] S2, adding nano-SiO2 particles to the softened P (VDF-HFP) matrix, and using an ultrasonic disperser to perform ultrasonic treatment for 30 to 60 minutes at a power of 60 to 100 W to achieve fine crushing of the nano-SiO2 particles and degassing of the solution to obtain a spinning solution;

[0019] S3. The spinning solution is extruded through the spinneret of the electrospinning process and spun into a film to obtain a P(VDF-HFP) / SiO2 composite nanofiber membrane.

[0020] Furthermore, the spinning voltage of the electrospinning process is 12 to 18 kV, the spinning flow rate is 0.9 to 1.2 mL / h, and the spinning distance is 12 to 18 cm.

[0021] Furthermore, the diameter of the fibers in the P(VDF-HFP) / SiO2 composite nanofiber membrane is 100-500nm.

[0022] Furthermore, the clothing fabric is cotton fabric, polyester fabric, nylon fabric or blended fabric.

[0023] Furthermore, the second step is a hot pressing process, wherein the hot pressing temperature of the hot pressing process is 85°C to 105°C and the operating pressure is 1.5 to 2.5 Kgf / m 2 , the pressing time is 10-15s.

[0024] The present application also discloses a radiation cooling nanofiber membrane composite clothing fabric prepared by any of the above preparation methods.

[0025] Principle explanation: The radiant cooling nanofiber membrane composite clothing fabric of the present invention achieves a multifunctional fusion of radiant cooling, high air permeability, and anti-fouling and easy cleaning by adopting a unique material combination and structural design of P(VDF-HFP) / SiO2 nanofiber membrane and EVA hot melt adhesive non-woven fabric; P(VDF-HFP) / SiO2 nanofiber membrane utilizes the high reflectivity and optimized mid-infrared radiation capability of SiO2 nanoparticles to effectively reflect sunlight and accelerate the dissipation of body heat to achieve an excellent cooling effect; the porous structure of EVA hot melt adhesive non-woven fabric enhances the air permeability of the fabric, promotes sweat evaporation while maintaining the stability of the fiber membrane structure, and improves durability; in addition, the hydrophobic properties imparted by SiO2 nanoparticles provide the fabric with excellent anti-fouling and easy-to-clean properties; this innovative sandwich structure design not only effectively exerts various functions, but also achieves an unexpected comprehensive performance improvement of 1+1>2 through the interaction of materials and structures, greatly enhancing the market competitiveness of clothing fabrics and the user wearing experience.

[0026] Beneficial effects:

[0027] The present application provides a radiation cooling nanofiber membrane composite clothing fabric and a preparation method thereof, which has the following beneficial effects compared with the prior art:

[0028] 1. The present application adopts a unique nanofiber membrane, which is composed of SiO2 nanoparticles with radiative cooling properties and a P (VDF-HFP) copolymer matrix with moisture absorption and perspiration wicking properties; the radiative cooling nanoparticles are evenly distributed in the nanofiber membrane, effectively reflecting sunlight to achieve a significant cooling effect, and the moisture absorption and perspiration wicking properties of P (VDF-HFP) ensure that the wearer's skin can remain dry; it achieves a perfect combination of radiative cooling and moisture absorption and perspiration wicking, not only achieving radiative cooling by reflecting sunlight, but also further improving the cooling effect by moisture absorption and evaporation, thereby creating an efficient synergistic cooling solution;

[0029] 2. Using the synergistic cooling technology, a series of fabrics and clothing have been successfully developed; the fabrics and clothing not only demonstrate excellent cooling function, but also have moisture absorption and perspiration performance, providing the wearer with a perspiration-wicking, cool and comfortable wearing experience. The design of fabrics and clothing takes into account the diverse needs of the wearer and is suitable for various environments and activities, such as sportswear, outdoor equipment, daily leisure, etc., meeting the market demand for high-performance, comfortable and breathable fabrics and clothing with synergistic cooling functions;

[0030] 3. The present application further optimizes the structure of the radiation cooling composite fabric, and significantly improves the overall performance of the fabric by using EVA hot melt adhesive non-woven fabric for hot pressing bonding; EVA hot melt adhesive non-woven fabric has the characteristics of low-temperature viscosity, and its operating temperature is 85-105°C, which is much lower than the dissolution temperature of P (VDF-HFP) nanofiber membrane 120-140°C, which can effectively save energy consumption, reduce production costs, and avoid high temperature damage to the nanofiber membrane to ensure its integrity; EVA hot melt adhesive non-woven fabric has high air permeability, which improves the comfort and functional performance of the fabric, so that the user can maintain good air permeability and cool feeling during wearing; EVA hot melt adhesive non-woven fabric is not easy to wrinkle or bubble during the hot pressing bonding process, which ensures that the composite fabric remains flat and beautiful during processing and use, and at the same time improves the durability and service life of the fabric; The use of EVA hot melt adhesive non-woven fabric as the bonding material for the radiation cooling composite fabric is not only superior to other materials in technical performance, but also excellent in economy and practicality, which comprehensively improves the overall performance of the fabric;

[0031] 4. The radiative cooling nanofiber membrane of this application has obvious advantages over existing fabrics in terms of cooling effect, air permeability, moisture permeability, softness and wearing comfort;

[0032] 5. The radiative cooling nanofiber membrane of this application achieves excellent cooling effect by reflecting visible light and infrared light in sunlight and utilizing infrared radiation mechanism;

[0033] 6. The micro-nanoscale fiber network structure of the radiative cooling nanofiber membrane of the present application enables it to have excellent air permeability and moisture absorption and perspiration removal functions, while maintaining a light and soft texture, providing a comfortable wearing experience, making the radiative cooling nanofiber membrane and clothing fabric composite material an ideal choice for the production of high-performance clothing, especially suitable for occasions that need to optimize and improve wearing comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the cross-sectional structure of the composite fabric of the radiative cooling nanofiber membrane and ordinary polyester fabric in Example 2 of the present application;

[0035] Figure 2 This is a schematic diagram of the cooling principle of the radiation refrigeration nanofiber membrane composite clothing fabric of the present application;

[0036] Explanation of the accompanying drawings: 1. Radiative cooling nanofiber membrane, 2. EVA hot melt adhesive non-woven fabric, 3. Polyester fabric. DETAILED DESCRIPTION

[0037] In this section, the specific embodiments of this patent application will be described in detail in conjunction with the accompanying drawings, aiming to provide a clear and comprehensive description of the technical solution. It should be clear that the embodiment described here only represents one of the possible applications of this patent and does not represent all possible implementation methods. Based on the content of this document, a person of ordinary skill in the art can derive all other potential embodiments covered by this application without performing any creative work. Therefore, these embodiments should all be deemed to be within the scope of protection of this patent.

[0038] Example 1

[0039] A method for preparing a radiation cooling nanofiber membrane composite clothing fabric, the steps are as follows:

[0040] The first step: using polyvinylidene fluoride-co-hexafluoropropylene P (VDF-HFP) as a matrix, and doping nano-SiO2 particles uniformly distributed in the P (VDF-HFP) copolymer to obtain a spinning solution, and preparing a P (VDF-HFP) / SiO2 composite nanofiber membrane, i.e., a radiation cooling nanofiber membrane, from the spinning solution by electrospinning technology, polyvinylidene fluoride-co-hexafluoropropylene P (VDF-HFP) was purchased from Sigma-Aldrich CAS No. 9011-17-0, product number 427160;

[0041] Step 2: The P(VDF-HFP) / SiO2 composite nanofiber membrane and clothing fabric are composited with EVA hot melt adhesive non-woven fabric to form a stable composite material, namely, the radiation refrigeration nanofiber membrane composite clothing fabric. The EVA hot melt adhesive non-woven fabric was purchased from Pinghu Zhanpeng Hot Melt Adhesive Film Co., Ltd., ZPME-web001.

[0042] The spinning solution is prepared by dissolving P(VDF-HFP) in a mixed solution of DMF and acetone, stirring and mixing at 50°C to 60°C for 1h to 2h, adding nano-SiO2 particles, and degassing by 60-100W ultrasound for 30-60min; the nano-SiO2 particles are hydrophobic silica, and acetone and DMF are used as solvents in the preparation process. These solvents will evaporate in the spinning process. The nanofibers formed by PVDF and silica have a fine fiber structure and high scattering properties, as well as the color of the material itself, which together make the electrostatically spun membrane appear white.

[0043] The mass percentage of polyvinylidene fluoride-co-hexafluoropropylene in the spinning solution is 10.65%, and the mass percentage of the hydrophobic silicon dioxide in the spinning solution is 0.45%.

[0044] The molar ratio of DMF to acetone in the mixed solution of DMF and acetone is DMF:acetone=6:4.

[0045] The spinning voltage of the electrospinning process was 15 kV, the spinning flow rate was 1.02 mL / h, and the spinning distance was 15 cm.

[0046] In order to enhance the efficiency of the radiative cooling fiber and ensure that the hydrophobic SiO2 nanoparticles are evenly dispersed in the P(VDF-HFP) copolymer, the traditional solution preparation method and electrospinning technology were cleverly combined to prepare the P(VDF-HFP) / SiO2 composite nanofiber membrane. The specific preparation method is as follows:

[0047] S1. Add polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) pellets into a mixed solution of DMF and acetone, and stir magnetically at 50°C to 60°C for 1h to 2h to obtain a softened P(VDF-HFP) matrix. During this process, the friction between the pellets and the solvent, between the pellets, and between the pellets and the wall of the device generates heat, which, aided by the external heating of the instrument, causes the P(VDF-HFP) copolymer to quickly enter a softened state and exhibit strong adhesion properties.

[0048] S2, adding nano-SiO2 particles to the softened P(VDF-HFP) matrix, and using an ultrasonic disperser to perform ultrasonic treatment for 30 to 60 minutes at a power of 60 to 100 W to achieve fine crushing of the nano-SiO2 particles and degassing of the solution to obtain a spinning solution; the surface treatment agent can perform more effective local treatment on the nano-particles, significantly reduce the surface energy of the particles, and avoid the re-aggregation of the hydrophobic SiO2 nano-particles. The viscous drag force of the P(VDF-HFP) copolymer and the high shear force generated by ultrasound work together to ensure uniform coating between the hydrophobic SiO2 nano-particles and the P(VDF-HFP) copolymer pellets;

[0049] S3, the spinning solution is extruded through the spinneret of the electrospinning process, and the spinning film is formed to obtain a P(VDF-HFP) / SiO2 composite nanofiber membrane. Through the uniform dispersion of hydrophobic SiO2 nanoparticles, the radiation cooling fiber of the present invention can achieve a more uniform radiation cooling effect, so that the cooling performance of the blended yarn product is also more uniform and stable; in addition, the uniform dispersion of hydrophobic SiO2 nanoparticles further smoothes the surface of the nanofiber membrane, which is conducive to improving the reflectivity of sunlight, thereby optimizing the cooling effect of the fabric.

[0050] The fabrics of the garments are cotton, polyester, nylon or blended fabrics.

[0051] The radiative cooling nanofiber membrane and polyester fabric are compounded with EVA hot melt adhesive non-woven fabric to form a stable composite material. The specific steps are as follows:

[0052] Step 1: Set the temperature of the hot pressing equipment to 85℃~105℃ and the operating pressure to 1.5~2.5Kgf / m 2, the pressing time is set to 10-15 seconds;

[0053] Step 2: The radiation cooling nanofiber membrane 1, the EVA hot melt adhesive non-woven fabric 2, and the polyester fabric 3 are stacked in sequence and aligned and fixed on the equipment workbench;

[0054] Step 3, start the hot pressing equipment, and perform hot pressing operation at a set temperature and pressure, so that the EVA hot melt adhesive non-woven fabric 2 is fully melted and firmly combined with the radiation cooling nanofiber membrane 1 and the polyester fabric 3 to obtain a composite fabric;

[0055] Step 4: The composite fabric is naturally cooled to room temperature and quality inspected to ensure that the surface is smooth, wrinkle-free, bubble-free, and that the bonding strength and air permeability meet the standards, thereby obtaining the radiation cooling nanofiber membrane composite clothing fabric. Clothing made of the radiation cooling nanofiber membrane composite clothing fabric has certain perspiration, cooling, and comfort effects.

[0056] Example 2

[0057] A method for preparing a radiation cooling nanofiber membrane composite clothing fabric, the steps are as follows:

[0058] The first step: using polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) (Sigma-Aldrich CAS No. 9011-17-0 product number 427160) as a matrix, and doping nano-SiO2 particles uniformly distributed in the P(VDF-HFP) copolymer to obtain a spinning solution, and preparing a P(VDF-HFP) / SiO2 composite nanofiber membrane, i.e., a radiation cooling nanofiber membrane, from the spinning solution by electrospinning technology;

[0059] Step 2: The P(VDF-HFP) / SiO2 composite nanofiber membrane and clothing fabric are compounded with EVA hot melt adhesive non-woven fabric to form a stable composite material, namely, the radiation cooling nanofiber membrane composite clothing fabric.

[0060] In the first step, the spinning solution is prepared by dissolving P(VDF-HFP) in a mixed solution of DMF and acetone, stirring and mixing at 50°C to 60°C for 1h to 2h, adding nano-SiO2 particles, and degassing at 60 to 100W ultrasound for 30 to 60min; the nano-SiO2 particles are hydrophobic silica.

[0061] The mass percentage of polyvinylidene fluoride-co-hexafluoropropylene in the spinning solution is 10.65%, and the mass percentage of the hydrophobic silicon dioxide in the spinning solution is 0.45%.

[0062] The molar ratio of DMF to acetone in the mixed solution of DMF and acetone is DMF:acetone=6:4.

[0063] The spinning voltage of the electrospinning process was 15 kV, the spinning flow rate was 0.9 mL / h, and the spinning distance was 15 cm.

[0064] In order to enhance the efficiency of the radiative cooling fiber and ensure that the hydrophobic SiO2 nanoparticles are evenly dispersed in the P(VDF-HFP) copolymer, the traditional solution preparation method and electrospinning technology were cleverly combined to prepare the P(VDF-HFP) / SiO2 composite nanofiber membrane. The specific preparation method is as follows:

[0065] S1. Add polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) pellets into a mixed solution of DMF and acetone, and stir magnetically at 50°C to 60°C for 1h to 2h to obtain a softened P(VDF-HFP) matrix. During this process, the friction between the pellets and the solvent, between the pellets, and between the pellets and the wall of the device generates heat, which, aided by the external heating of the instrument, causes the P(VDF-HFP) copolymer to quickly enter a softened state and exhibit strong adhesion properties.

[0066] S2, adding nano-SiO2 particles to the softened P(VDF-HFP) matrix, and using an ultrasonic disperser to perform ultrasonic treatment for 30 to 60 minutes at a power of 60 to 100 W to achieve fine crushing of the nano-SiO2 particles and degassing of the solution to obtain a spinning solution; the surface treatment agent can perform more effective local treatment on the nano-particles, significantly reduce the surface energy of the particles, and avoid the re-aggregation of the hydrophobic SiO2 nano-particles. The viscous drag force of the P(VDF-HFP) copolymer and the high shear force generated by ultrasound work together to ensure uniform coating between the hydrophobic SiO2 nano-particles and the P(VDF-HFP) copolymer pellets;

[0067] S3, the spinning solution is extruded through the spinneret of the electrospinning process, and the spinning film is formed to obtain a P(VDF-HFP) / SiO2 composite nanofiber membrane. Through the uniform dispersion of hydrophobic SiO2 nanoparticles, the radiation refrigeration fiber of the present invention can achieve a more uniform radiation refrigeration effect, so that the cooling performance of the blended yarn product is also more uniform and stable. In addition, the uniform dispersion of hydrophobic SiO2 nanoparticles further smoothes the surface of the nanofiber membrane, which is conducive to improving the reflectivity of sunlight, thereby optimizing the cooling effect of the fabric.

[0068] The clothing fabric is polyester fabric.

[0069] The radiative cooling nanofiber membrane and polyester fabric are compounded with EVA hot melt adhesive non-woven fabric to form a stable composite material. The specific steps are as follows:

[0070] Step 1: Set the temperature of the hot pressing equipment to 85℃~105℃ and the operating pressure to 1.5~2.5Kgf / m 2, the pressing time is set to 10-15 seconds;

[0071] Step 2: The radiation cooling nanofiber membrane 1, the EVA hot melt adhesive non-woven fabric 2, and the polyester fabric 3 are stacked in sequence and aligned and fixed on the equipment workbench;

[0072] Step 3, start the hot pressing equipment, and perform hot pressing operation at a set temperature and pressure, so that the EVA hot melt adhesive non-woven fabric 2 is fully melted and firmly combined with the radiation cooling nanofiber membrane 1 and the polyester fabric 3 to obtain a composite fabric;

[0073] Step 4: The composite fabric is naturally cooled to room temperature and quality inspected to ensure that the surface is smooth, wrinkle-free, bubble-free, and that the bonding strength and air permeability meet the standards, thereby obtaining the radiation cooling nanofiber membrane composite clothing fabric.

[0074] Clothing made of radiation cooling nanofiber membrane composite clothing fabric has certain perspiration, cooling and comfort effects.

[0075] In the embodiment of this patent, a unique design of a radiation cooling nanofiber membrane is introduced, which effectively achieves the purpose of reflecting visible light and infrared light in sunlight and utilizing the mechanism of infrared radiation to penetrate the atmosphere through the atmospheric window (8μm to 13μm band) to emit heat, thereby promoting cooling. The radiation cooling nanofiber membrane is composed of a P (VDF-HFP) copolymer matrix, in which SiO2 nanoparticles are evenly distributed, forming a P (VDF-HFP) / SiO2 nanofiber membrane. Figure 1 The radiation cooling principle shown demonstrates the process when the full spectrum of sunlight is irradiated to the surface of the P(VDF-HFP) / SiO2 nanofiber membrane. The nanofiber membrane can effectively reflect part of the light, including visible light and infrared light. Through a specific atmospheric window (8μm~13μm band), the membrane can emit heat in the form of a mid-infrared band and penetrate the atmosphere, thereby achieving an excellent radiation cooling effect. Through sophisticated material design and structural optimization, the present invention enables the P(VDF-HFP) / SiO2 nanofiber membrane to not only perform well in reflecting sunlight, but also effectively emit heat through a unique infrared radiation mechanism, providing an innovative solution for efficient cooling.

[0076] By utilizing the unique structural characteristics of the nanofiber membrane, the present invention significantly enhances the moisture absorption and perspiration wicking ability of the fabric. The nanofiber membrane adopts a fine micro-nanoscale fiber network structure, which has an extremely high surface area and unique porosity, providing an ideal channel for the absorption and transmission of water molecules. When the wearer performs high-intensity activities and produces sweat, these micro-nanoscale fibers can quickly absorb and disperse the sweat, and discharge the sweat outward through the pores between the fibers. In addition, the structure of this nanofiber membrane can effectively prevent sweat from accumulating on the skin surface while maintaining good air permeability, thereby reducing the dampness and discomfort of the skin. While improving the moisture absorption and perspiration efficiency, the nanofiber membrane also maintains a light and soft texture to ensure wearing comfort. By optimizing the moisture absorption and perspiration wicking performance of the nanofiber membrane, the present invention is not only suitable for wearing in high temperature environments, but also suitable for use in sports and outdoor activities, providing the wearer with a lasting dry experience and comfort. This nanofiber membrane, which combines efficient moisture absorption and perspiration wicking with a comfortable wearing experience, demonstrates the breakthrough and application potential of the present invention in fabric technology innovation.

[0077] In the embodiment of the present invention, we focus on the compatibility of the Si-O-Si bond vibration absorption peak in SiO2 with the atmospheric window band, which significantly enhances the emissivity in the mid-infrared band. Therefore, the mass percentage of SiO2 nanoparticles in the radiation cooling fiber directly affects the radiation cooling effect. It should be noted that if the content of hydrophobic SiO2 nanoparticles is too high, it will cause excessive agglomeration of nanoparticles during the spinning process. In order to optimize this effect and ensure the maximization of the radiation cooling performance, in this embodiment, we specifically select the mass percentage of hydrophobic silica in the radiation cooling fiber to be 0.45% to 1.75%. At the same time, in order to ensure that the P(VDF-HFP) / SiO2 nanofiber membrane has excellent radiation cooling effect and stable solar reflectivity, the mass percentage of P(VDF-HFP) is set between 10.50% and 10.75%. Such a configuration not only ensures the high efficiency of the radiation cooling fiber, but also helps to maintain the overall stability and performance of the fiber membrane.

[0078] Example 3

[0079] A method for preparing a radiation cooling nanofiber membrane composite clothing fabric, the steps are as follows:

[0080] The first step: using polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) (Sigma-Aldrich CAS No. 9011-17-0 product number 427160) as a matrix, and doping nano-SiO2 particles uniformly distributed in the P(VDF-HFP) copolymer to obtain a spinning solution, and preparing a P(VDF-HFP) / SiO2 composite nanofiber membrane, i.e., a radiation cooling nanofiber membrane, from the spinning solution by electrospinning technology;

[0081] Step 2: The P(VDF-HFP) / SiO2 composite nanofiber membrane and clothing fabric are compounded through EVA hot melt adhesive non-woven fabric (Pinghu Zhanpeng Hot Melt Adhesive Film Co., Ltd., ZPME-web001) to form a stable composite material, namely, the radiation cooling nanofiber membrane composite clothing fabric.

[0082] The spinning solution is prepared by dissolving P(VDF-HFP) in a mixed solution of DMF and acetone, stirring and mixing at 50-60°C for 1-2h, adding nano-SiO2 particles, and degassing at 60-100W ultrasound for 30-60min; the nano-SiO2 particles are hydrophobic silicon dioxide.

[0083] The mass percentage of polyvinylidene fluoride-co-hexafluoropropylene in the spinning solution is 10.65%, and the mass percentage of the hydrophobic silicon dioxide in the spinning solution is 0.45%.

[0084] The molar ratio of DMF to acetone in the mixed solution of DMF and acetone is DMF:acetone=6:4.

[0085] The spinning voltage of the electrospinning process was 15 kV, the spinning flow rate was 1.2 mL / h, and the spinning distance was 15 cm.

[0086] In order to enhance the efficiency of the radiative cooling fiber and ensure that the hydrophobic SiO2 nanoparticles are evenly dispersed in the P(VDF-HFP) copolymer, the traditional solution preparation method and electrospinning technology were cleverly combined to prepare the P(VDF-HFP) / SiO2 composite nanofiber membrane. The specific preparation method is as follows:

[0087] S1. Add polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) pellets into a mixed solution of DMF and acetone, and stir magnetically at 50°C to 60°C for 1h to 2h to obtain a softened P(VDF-HFP) matrix. During this process, the friction between the pellets and the solvent, between the pellets, and between the pellets and the wall of the device generates heat, which, aided by the external heating of the instrument, causes the P(VDF-HFP) copolymer to quickly enter a softened state and exhibit strong adhesion properties.

[0088] S2, adding nano-SiO2 particles to the softened P(VDF-HFP) matrix, and using an ultrasonic disperser to perform ultrasonic treatment for 30 to 60 minutes at a power of 60 to 100 W to achieve fine crushing of the nano-SiO2 particles and degassing of the solution to obtain a spinning solution; the surface treatment agent can perform more effective local treatment on the nano-particles, significantly reduce the surface energy of the particles, and avoid the re-aggregation of the hydrophobic SiO2 nano-particles. The viscous drag force of the P(VDF-HFP) copolymer and the high shear force generated by ultrasound work together to ensure uniform coating between the hydrophobic SiO2 nano-particles and the P(VDF-HFP) copolymer pellets;

[0089] S3, the spinning solution is extruded through the spinneret of the electrospinning process, and the spinning film is formed to obtain a P(VDF-HFP) / SiO2 composite nanofiber membrane. Through the uniform dispersion of hydrophobic SiO2 nanoparticles, the radiation cooling fiber of the present invention can achieve a more uniform radiation cooling effect, so that the cooling performance of the blended yarn product is also more uniform and stable; in addition, the uniform dispersion of hydrophobic SiO2 nanoparticles further smoothes the surface of the nanofiber membrane, which is conducive to improving the reflectivity of sunlight, thereby optimizing the cooling effect of the fabric.

[0090] The fabrics of the garments are cotton, polyester, nylon or blended fabrics.

[0091] The radiative cooling nanofiber membrane and polyester fabric are compounded with EVA hot melt adhesive non-woven fabric to form a stable composite material. The specific steps are as follows:

[0092] Step 1: Set the temperature of the hot pressing equipment to 85℃~105℃ and the operating pressure to 1.5~2.5Kgf / m 2 , the pressing time is set to 10-15 seconds;

[0093] Step 2: The radiation cooling nanofiber membrane 1, the EVA hot melt adhesive non-woven fabric 2, and the polyester fabric 3 are stacked in sequence and aligned and fixed on the equipment workbench;

[0094] Step 3, start the hot pressing equipment, and perform hot pressing operation at a set temperature and pressure, so that the EVA hot melt adhesive non-woven fabric 2 is fully melted and firmly combined with the radiation cooling nanofiber membrane 1 and the polyester fabric 3 to obtain a composite fabric;

[0095] Step 4: The composite fabric is naturally cooled to room temperature and quality inspected to ensure that the surface is smooth, wrinkle-free, bubble-free, and that the bonding strength and air permeability meet the standards, thereby obtaining the radiation cooling nanofiber membrane composite clothing fabric. Clothing made of the radiation cooling nanofiber membrane composite clothing fabric has certain perspiration, cooling, and comfort effects.

[0096] Comparative Example 1

[0097] A plain white polyester fabric, also the base fabric. The fabric has a loose structure, excellent air permeability, and limited radiant cooling capabilities.

[0098] Comparative Example 2

[0099] The difference from Example 1 is that the mass percentage of P(VDF-HFP) in the spinning solution is 10.70%, and the mass percentage of hydrophobic silica in the spinning solution is 0%.

[0100] Comparative Example 3

[0101] The difference from Example 2 is that the mass percentage of P(VDF-HFP) in the spinning solution is 10.60%, and the mass percentage of hydrophobic silica in the spinning solution is 0.90%.

[0102] Comparative Example 4

[0103] The difference from Example 2 is that the mass percentage of P(VDF-HFP) in the spinning solution is 10.55%, and the mass percentage of hydrophobic silica in the spinning solution is 1.30%.

[0104] Comparative Example 5

[0105] The difference from Example 2 is that the mass percentage of P(VDF-HFP) in the spinning solution is 10.50%, and the mass percentage of hydrophobic silica in the spinning solution is 1.75%.

[0106] The synergistic cooling functional fabrics in Examples 1-3 and Comparative Examples 1-5 were tested for radiative cooling performance and air permeability, and the results are shown in Table 1. The testing conditions for radiative cooling performance, air permeability and hydrophobicity are: ambient temperature 30°C, convection heat release coefficient 10 W / m 2 *K, air mass AM1.6, atmospheric pressure 100Pa. The test method for radiant cooling performance is outdoor daytime cooling test, the test index is temperature difference, the smaller the value, the better the effect; the test method for air permeability is the standard test method for material gas permeability, the test index is air permeability, the higher the air permeability, the better the air permeability of the fabric, the better the thermal comfort of the fabric. The test standard for hydrophobic performance is contact angle, the larger the contact angle, the better the hydrophobic performance, the better the anti-fouling and dirt resistance effect.

[0107] Table 1

[0108]

[0109] From the results in Table 1, it can be seen that the fabric in Example 1 is made of a radiation cooling nanofiber membrane composited with an ordinary polyester fabric, and a radiation cooling effect and anti-fouling performance with a better synergistic effect are obtained.

[0110] Compared with Example 1, the radiation cooling effect of Example 2 and Example 3 is poor. This is because different spinning flow rates will have a significant impact on the morphology and quality of the fiber. A flow rate that is too fast will increase the amount of polymer solution sprayed, which will increase the fiber diameter; a flow rate that is too slow will reduce the amount of polymer solution sprayed and reduce the fiber diameter. At the same time, a flow rate that is too fast will cause the sprayed fibers to be unable to fully stretch under the action of the electric field, which is prone to fiber entanglement or adhesion; and a flow rate that is too slow may cause uneven accumulation of fibers on the collector, affecting the uniformity and performance of the final product. When the spinning flow rate is 1.02mL / h, the radiation cooling effect is optimal.

[0111] Compared with Comparative Example 1, the radiation cooling effect of Comparative Example 2 is slightly improved, but not obvious. At the same time, the air permeability and hydrophobicity change significantly. This is because the unique microstructure and material properties of the P (VDF-HFP) nanofiber membrane can effectively reflect and scatter infrared rays in the sun, thereby reducing the temperature of the surface of the clothing, and the nanofiber material can be designed to be highly hydrophobic through its surface properties, helping the fabric to resist moisture and stains more effectively. However, due to the presence of the membrane, the pores may be partially blocked, reducing air circulation, which slightly affects its air permeability, but compared with the standard clothing air permeability (700mm / s), it meets and exceeds the clothing standard.

[0112] Compared with Example 1, the radiation cooling performance and moisture permeability of Comparative Example 2 are not as good as those of Example 1. Although both use polyester base cloth as the supporting material, a layer of nanofiber membrane composed of P (VDF-HFP) and SiO2 is compounded. However, in Example 1, by adding SiO2 nanoparticles to the nanofiber membrane, the emissivity of the fabric in the atmospheric window band (8μm~13μm) is effectively enhanced. The Si-O-Si bond vibration absorption peak of SiO2 nanoparticles matches this band, thereby improving the radiation cooling effect. In contrast, although Comparative Example 2 also uses a nanofiber membrane of P (VDF-HFP), SiO2 nanoparticles are not added, so the radiation cooling performance is not as good as that of Example 1. In addition, the addition of SiO2 may also improve the air permeability of the fabric, making Example 1 more superior in terms of air permeability.

[0113] Compared with Example 1, the radiation cooling effect of Comparative Examples 3, 4, and 5 is weakened. Increasing the content of SiO2 changes the optical properties of the nanofiber membrane, especially its emissivity in the atmospheric window band. If the distribution or particle size of SiO2 is uneven, it may lead to a decrease in emissivity, thereby reducing the radiation cooling effect. At the same time, a higher SiO2 content will enhance the thermal conductivity of the nanofiber membrane, resulting in an increase in the efficiency of heat transfer within the material, reducing the heat radiated from the surface to the external environment.

[0114] The above description has fully disclosed the specific embodiments of the present invention. It should be pointed out that any changes made by those skilled in the art to the specific embodiments of the present invention do not deviate from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the above specific embodiments.

Claims

1. A method for preparing a radiation cooling nanofiber membrane composite clothing fabric, characterized in that: Here are the steps: The first step: using polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) as a matrix and doping nano-SiO2 particles uniformly distributed in the P(VDF-HFP) copolymer to obtain a spinning solution, and preparing a P(VDF-HFP) / SiO2 composite nanofiber membrane, i.e., a radiation cooling nanofiber membrane, from the spinning solution by electrospinning technology; Step 2: The P(VDF-HFP) / SiO2 composite nanofiber membrane and clothing fabric are compounded with EVA hot melt adhesive non-woven fabric to form a stable composite material, namely, the radiation cooling nanofiber membrane composite clothing fabric.

2. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 1, characterized in that: In the first step, the spinning solution is prepared by dissolving P(VDF-HFP) in a mixed solution of DMF and acetone, stirring and mixing at 50°C to 60°C for 1h to 2h, adding nano-SiO2 particles, and degassing at 60 to 100W ultrasound for 30 to 60min; the nano-SiO2 particles are hydrophobic silica.

3. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 2, characterized in that: The mass ratio of nano-SiO2 particles: P (VDF-HFP) = 4-5:

100.

4. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 2, characterized in that: The molar ratio of DMF to acetone in the mixed solution of DMF and acetone is DMF:acetone=6:

4.

5. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 4, characterized in that: The specific preparation method of P(VDF-HFP) / SiO2 composite nanofiber membrane is as follows: S1, adding polyvinylidene fluoride-co-hexafluoropropylene P (VDF-HFP) pellets into a mixed solution of DMF and acetone, and magnetically stirring at 50° C. to 60° C. for 1 h to 2 h to obtain a softened P (VDF-HFP) matrix; S2, adding nano-SiO2 particles to the softened P (VDF-HFP) matrix, and using an ultrasonic disperser to perform ultrasonic treatment for 30 to 60 minutes at a power of 60 to 100 W to achieve fine crushing of the nano-SiO2 particles and degassing of the solution to obtain a spinning solution; S3. The spinning solution is extruded through the spinneret of the electrospinning process and spun into a film to obtain a P(VDF-HFP) / SiO2 composite nanofiber membrane.

6. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 5, characterized in that: The spinning voltage of the electrospinning process is 12 to 18 kV, the spinning flow rate is 0.9 to 1.2 mL / h, and the spinning distance is 12 to 18 cm.

7. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 1, characterized in that: The diameter of the fibers in the P(VDF-HFP) / SiO2 composite nanofiber membrane is 100-500nm.

8. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 1, characterized in that: The fabrics of the garments are cotton, polyester, nylon or blended fabrics.

9. The method for preparing the radiation cooling nanofiber membrane composite clothing fabric according to claim 1, characterized in that: The second step is hot pressing. The hot pressing temperature of the hot pressing process is 85℃~105℃ and the operating pressure is 1.5~2.5Kgf / m 2 , the pressing time is 10-15s.

10. A radiation cooling nanofiber membrane composite clothing fabric prepared by any preparation method of claims 1-9.

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